Please advise on A/C conversion

[GMBCHEF at aol.com]

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[ Picked text/plain from multipart/alternative ]
  I'll answer that for ya since you've been so helpful to me!
  There's a capillary tube that has one end inserted through the evaporator
and the other end goes to a relay mounted on the right side of the evaporator
with 2 connections on it. The tube measures the temp of the air surrounding
the evaporator, tells the relay which cycles the compressor so the evaporator
or the expansion valve won't freeze up.
 At least that's what I've gathered from my searching the archives and
talking to my technician.
 Sound about right guys?
HTH
Gary